Abstract: As flexible actuators and sensors, ion exchange polymer-metal composites (IPMCs) are widely used in bionic machinery, medical devices and other fields. Actuation is the main application of the IPMC, and IPMC actuators have bottlenecks such as low output power and unstable actuation. Sensing is another important application, and IPMC sensors endure some defects such as low induced voltage and large interference. For actuator, we discussed the modification techniques and driving characteristics of different polymer electrolytes, and focused on the structure-activity relationship of that, the compositions and structures the electrolytes determine their physical properties (e.g., ion exchange capacity, water uptake, mechanical property), subsequently determine their electromechanical properties (e.g., displacement, force outputs). For sensor, we discussed the optimization technologies of IPMC sensing properties (e.g., amplitude and stability of the induced voltage) from three aspects of electrode shape, electrolyte membrane structure and electrolyte ion size. We also discussed IPMC's future research.